The present invention generally relates to vehicle suspensions and, more particularly, relates to vehicle suspension capable of providing a kneeling function.
As is well known, transit vehicles, such as buses, occasionally employ means to aid the elderly or handicap board the vehicle. Although ramps and lifts have often been used, recently there has been a renewed interest in systems that enable the transit vehicle to be lowered. Theses systems are often known as kneeling systems, since they enable the transit vehicle to xe2x80x9ckneelxe2x80x9d toward the ground.
Kneeling systems often include a control device that actuates a plurality of pneumatic or hydraulic members to lower the step height of the transit vehicle to permit easy ingress and egress and later raising the vehicle back up for conventional locomotion. These kneeling systems may serve a dual purpose of also providing a leveling mechanism that automatically maintains a predetermined relationship between the vehicle chassis and the road wheels. Although these systems are generally satisfactory, there is a desire to provide a simplified and cost effective alternative to the conventional, rather complicated systems.
Accordingly, there exists a need in the relevant art to provide a kneeling valve assembly for use in a transit vehicle that is capable of lowering and raising a transit vehicle to aid in ingress to and egress from the vehicle. Furthermore, there exists a need in the relevant art to provide a kneeling valve assembly that is simplified and cost-effective to operate and maintain. Still further, there exists a need in the relevant art to provide a kneeling valve assembly that overcomes the disadvantages of the prior art.
According to the principles of the present invention, a kneeling valve assembly for transport vehicles is provided having an advantageous construction so as to enable quick and convenient kneeling operation of the transport vehicle to permit safe ingress and egress from the vehicle. The kneeling valve assembly employs a suspension member positioned between the vehicle body and the axle of the transport vehicle to raise and lower the transport vehicle relative to a ground level. The kneeling valve assembly includes a first valve that is operable to selectively permit fluid flow between the inlet passage and the suspension member to raise the transport vehicle relative to the ground level. A second valve is provided that is operable to selectively permit fluid flow between the suspension member and the exhaust passage to lower the transport vehicle relative to the ground level. A leveling trigger is fluidly coupled to the inlet passage and is operable to determine a height of the transport vehicle relative to the ground level. Finally, a third valve is provided that is operable to selectively permit fluid flow between the inlet passage and the suspension member to maintain a predetermined height above the ground level.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit,the scope of the invention.